| US 7,477,189 B2 | ||
| Methods and systems for acquisition, reacquisiton and tracking of weak navigational signals | ||
| Chi-Shin Wang, Half Moon Bay, Calif. (US); Zhike Jia, San Jose, Calif. (US); Yue-Meng Chen, Shanghai (China); Jian Cheng, Guangzhou (China); and EnYuan Tu, Shanghai (China) | ||
| Assigned to SiRF Technology Holdings, Inc., San Jose, Calif. (US) | ||
| Filed on Mar. 30, 2007, as Appl. No. 11/694,786. | ||
| Claims priority of provisional application 60/887328, filed on Jan. 30, 2007. | ||
| Prior Publication US 2008/0180321 A1, Jul. 31, 2008 | ||
| Int. Cl. G01S 5/14 (2006.01); G01S 1/04 (2006.01) | ||
| U.S. Cl. 342—357.15 [342/357.12] | 33 Claims |
| 1. A method of operating a navigational receiver under weak signal conditions, comprising:
correlating a received signal with a local signal to obtain correlation samples;
grouping consecutive correlation samples into sub-blocks;
compensating the frequency and phase of the samples in each sub-block;
determining frequency components of the sub-blocks;
determining a frequency compensation based on the frequency components;
performing a long coherent integration over a block of consecutive sub-blocks; and
using a reference signal from an external communication system.
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